Apparatus for heat treating electrotype printing plates



Sept. 13, 1938. H. M. BLAETZ 2,129,904

APPARATUS FOR HEAT TREATING ELECTRQTYPE PRINTING PLATES Filed Dec. 15;1937 w 6 W V L Mar 51 QAAIW JIV'O/P/VEY,

Patented Sept. 13, 1938 UNITED STATES PATENT OFFICE APPARATUS FOR HEATTREATING ELEC- TROTYPE PRINTING PLATES Application December 15, 1937,Serial No. 179,927

3 Claims.

It has been found that heating electrotyp'e printing plates to acritical temperature of about 460470 F., followed by rapid cooling (asby quenching at a temperature of 45-65 F.), produces an extreme softnessof the plate alloy, followed by a rapid increase in hardness andtoughness. This results in an improved printing plate which is betterable to resist wear and fracture during long runs on a printing press.

Various methods of carrying out this heat treatment have been proposedand tried. One method heats the plate in oil. I have found thatmaintaining an oil bath at 460-470 F., causes appreciable loss of'oil byevaporation; condensation of the evaporated portion results in an oilydeposit of carbon or soot on the walls and ceiling of the workroom, oron the surfaces of a ventilating hood or cover which may be provided tocarry away or confine the fumes. Further, the use of the oil heatingbath not only provides a fire hazard but also requires in addition tothe quenching bath, the use of a cleaning solution for removing the oilfilm from the printing plate surfaces. These features are objectionablein practical operation, especially where large numbers of plates areheat-treated.

The use of high-boiling synthetic liquids, such as diphenyl or triphenyloxides or mixtures of these, has also been proposed. I have found thatobjectionable fumes are given off at the high temperatures necessary,and that the loss of liquid would require the use of elaborate equipmentfor reclaiming the vapors.

Still another proposed method involves the use of chemical salts whichare solid at ordinary temperatures, but which are liquid at temperaturesabove, say, 200 F. The use of such salts in a plate heating batheliminates the fumes and evaporation. However, I have found that platesheated in this manner will carry a thin film of molten salt whichsolidifies as soon as the plate is immersed in the cold quenchingmedium. This film tend to prevent uniform cooling by the quenchingmedium. When I have tested different areas of plates so heated andquenched, I have found that the hardness is not uniform. The insulatingeffect of the salt film has resulted in some areas being solt and othersextremely hard. It is desirable that the plate should be of uniformhardness in all areas.

I have found a simple, effective, and practical means of eliminating theobjectionable features of the methods which have been discussed.

The principal objects of the present invention are to avoid the use ofobjectionable liquids as heating media and to eliminate dangerous firehazards; to minimize the floor space required; to avoid undue escape ofheat; to provide ready ingress and egress for the plates; to heat treateither flat or curved plates; to provide capacity 5 for treating a largenumber of plates and to make the operation substantially automatic.

Other objects of the invention will appear from the followingdescription at the end of which the invention will be claimed.

Generally stated the invention comprises a tank adapted to contain waterand provided with cooling means, a heat insulated conical hood closed atits top and open at its bottom and superposed above and spaced from thetank and covering a portion of the water therein, means for heating airentering the hood, heat insulated trays conforming to the shape of theprinting plates and adapted to support the plates when heated and toprotect the faces of the plates from over heating, a conveyor of whichone flight or reach extends above the water in the tank and up into thetop part of the hood and of which another flight or reach extendsdownwards from the top part and out of the hood and between the liquidin the tank and the first flight of the conveyor, said trays beingpendent from the conveyor and presented outside of the hood for thereception of the plates and being carried by the conveyor into and upand down in the hood to heat the plates, and into and thru the water inthe tank to quench the plates, and out of the water in the tank todeliver the plates.

The invention also comprises the improvements to be presently describedand finally claimed. 7

In the following description reference will be made to the accompanyingdrawing forming part hereof and in which,

Figure 1 is a longitudinal central section of apparatus embodyingfeatures of the invention, and

Fig. 2 is a transverse vertical section of the same.

In the drawing I indicates a tank adapted to contain quenching fiuid andit is provided with cooling coils 2, it may conveniently be arrangedupon the floor. 3 is a heat insulated conical hood closed at its top andopen at its bottom, the hood is superposed above the tank and it may besupported as indicated for example at 4. 5 indicates means as burnersfor heating air entering the hood and for keeping the air in the hoodhot. 6 are trays adapted to support the plates. The trays 6 may be fiator curved in order to conform to the shape of the printing plate. Thetrays are faced with insulating material I, which is not affected by theliquid in the tank I, and which prevents overheating the nickle andcopper shell of the plates which if overheated would cause the thinlayer of tin which bonds the shell to the plate alloy to be drawn awayby the antimony with the result that the bond is materially weakened ifnot destroyed. The trays 6 are pendent from the conveyor 8, and arepresented outside of the hood toward the right in Fig. 1, for thereception of the printing plates and they are carriedby the conveyor 8into and up and down in the hood to heat the plates, and into and thruthe water in the tank I to quench the plates, and out of the water inthe tank to deliver the plates. Thev trays are each provided with alaterally disposed arm 9 by which they are pendent. There are lever.elements centrally pivoted to the conveyor and to one arm ID, of whichthe trays are pivotally attached in generally horizontal position in allpositions of the .lever elements. II are curved guides located in thepath of the ends of the other arms [2 of the lever elements. Thesecurved guides operate on the arms I2 to turn-the same so that the traysare dropped quickly into the quenching fluid as indicated toward theleft of the tank I in the drawing.

If desired automatic feeding means may be employed for placing theprinting plates on the trays 6, and for removing them, although suchmeans are not shown in the drawing because they are not a part of thepresent invention.

The conveyor 8 passes around suitable guide wheels 13, I6, I and I6, andat l1 there is indicated means for driving the conveyor.

It will be obvious to those skilled in the art to which the inventionrelates that modifications may be made in details of construction andarrangement without departing from thespirit of the invention which isnot limited as to such matters or otherwise than the prior art and theappended claims may require.

I claim:

1. Apparatus for heat treating electrotype printing plates comprising incombination a tank adapted to contain a quenching fluid, an open bottomhood arranged above the tank and having means for heating its interior,an endless conveyor extending into and up and down in the hood andhaving a flight extending out of the hood horizontally above the levelof the quenching fluid, trays having insulated faces, lever elementscentrally pivoted to the conveyor and to one arm of which the trays arepivotally attached and are pendent in generally horizontal position inall positions of the lever elements, and curved guides located at theentrance of said flight of the conveyor and in the path of the ends ofthe other arms of said lever elements to turn the same and drop thetrays quickly into the quenching fluid.

2. Apparatus for heat treating electrotype printing plates comprising incombination a tank adapted to contain water and provided with coolingmeans, a heat insulated conical hood closed at its top and open at itsbottom and superposed above and spaced from the tank and covering aportion of the water therein, means for heating air entering the hood,heat insulated trays conforming to the shape of the printing plates andadapted to support the plates when heated and to protect the faces ofthe plates from overheating, a conveyor of which one flight or reachextends above the water in the tank and up into the-top part of the hoodand of which another flight or reach extends downwards from the top partof and out of the hood and between the liquid in the tank and the firstflight of the conveyor, said trays being pendent from the conveyor andpresented outside of the hood for the reception of plates andbeingcarried by the conveyor into and up and down in the hood to heatthe plates and into and thru the waterin the tank to quench the plates,and out of the water in the tank to deliver the plates, said trays eachbeing provided with a laterally disposed arm by which it is pendent.

3. Apparatus for heat treating electrotype printing plates comprising incombination a tank adaptedto contain water, a heat insulated hoodsuperposed above and spaced from the tank, means for heating the. hood,trays conforming to the shape of the printing plates and adapted tosupport the plates when heated, a conveyor of which one flight or reachextends above the water in the tank and up into the top part of thehood, and of which another flight or reach extends downwards from thetop part of and out .of the hood and between the liquid in the tank andthe first flight of the conveyor, said trays being pendent from theconveyor and presented outside of the hood for the reception of platesand being carried by the conveyor into and up and down in the hood toheat the plates and into and through the waterv inthe tank to quench theplates and out of the water in the tank to deliver the plates.

HARRY M. BLAE'IZ.

